Scopimera philippinensis Wong, Shih & Chan, 2011, sp. nov.

Scopimera philippinensis sp. nov.

(Figs. 5 a–d, 6a–b, 7a–b, 8)

Material examined. HOLOTYPE: 3 (NMCR-28030), Iloilo, Panay I., the Philippines, 20 Nov 2009, coll. K.J.H. Wong & D.K.H. Lo. PARATYPES: 23 1Ƥ (NSMT-Cr 16011), Villa beach, Iloilo, Panay I., Philippines, 20 Feb 2004, coll. M. Komatsu & M. Takeda; 73 4ƤƤ (CEL-Sco-Phi-001), data same as holotype; 23 (NMNS-6495- 001), data same as holotype; 23 (NMCR-28031), data same as holotype; 23 1Ƥ (ZRC-2010.0017), data same as holotype.

Comparative material. Scopimera curtelsona: 123 18ƤƤ (CEL-Sco-Hainan-001), Wenchang, Hainan Island, China, 2 Dec 2008, coll. K.J.H. Wong et al.

Diagnosis. Carapace globular, broader than long, surface generally smooth except on branchial regions (Fig. 5 a). External maxilliped merus smaller than ischium, joint oblique (Fig. 5 b); triangular tooth present on inner margin of cheliped dactylus (Fig. 5 c). G1 slender, tip rounded, surrounded with brush of setae, among which one very long seta extends prominently (Fig. 6 a, b).

Description. Carapace inflated, width at least 1.5 times as length, longitudinally arched, latitudinally cylindrical, most raised across branchial regions; surface divided by shallow grooves; longitudinal groove along front, extending 1/4 of carapace length marked; curved, rounded “M-shaped” groove surrounding anterior, lateral of cardiac region slightly shallower; surface smooth except for several sparsely distributed, rounded flat tubercles at summits of raised branchial regions (Fig. 5 a). Eyes situated on elongated stalks, orbits oblique when viewed above (Fig. 5 a). External orbital angle as acute triangle, not extending beyond lateral margins; ridge along lateral margins faintly defined if present (Fig. 5 a). Lateral margins diverge posteriorly, distance between both external orbital angles less than that across bases of the last ambulatory legs (Figs. 5 a, 8). External maxillipeds convex, merus slightly smaller than ischium, joint between which straight, oblique (Fig. 5 b). Ventral surface almost entirely glabrous except dense tufts of soft setae between bases of first, second ambulatory legs; thin light-colored setae sparsely scattered around bases of appendages.

Entire cheliped covered in fine granules, total length slightly more than carapace length; merus with single longitudinal ovate tympana on proximal half of inner surface; carpus subequal to merus in length, ovate; palm as long as fingers, shorter than carpus; fingers slender, distal ends taper into sharp tips, inner margin of dactylus armed with triangular tooth, that of both fingers weakly serrated with beaded tubercles (Fig. 5 c). Ambulatory legs slender, elongated, second leg longest, slightly longer than first, fourth leg shortest; each merus compressed, tympana entire, occupying most of the segment, carpus slightly shorter than propodus, dactylus tapers to sharp tip. Thin, light-colored setae very sparsely distributed along both margins of merus, posterior margins of all legs.

Male abdomen elongated, telson distally rounded, broader than long, lateral margins subparallel on proximal half; sixth somite broader than long, distal margin longer than proximal; fifth somite longer than broad, slightly trapezoidal, proximal margin concave, approximately 2/3 as long as distal; fourth somite broad, lateral margins diverge posteriorly (Fig. 5 d). G1 slender, curving dorsally, tapering to rounded tip; brush of setae near distal inner curve, among which extends a single conspicuous extremely long seta (Fig. 6 a, b). Female abdomen roughly circular, telson semicircular; sixth somite distinctly broader than telson, both distal angles rounded; fifth, sixth somites with same width, broader than long, lateral borders subparallel.

Size. CW 4.3 mm, CL 3.0 mm for the holotype male (Fig. 8).

Coloration. Carapace grayish brown, faintly reddish when alive (Fig. 7 a). Appendages banded with dark patches (Figs. 7 a, b, 8). External maxillipeds creamish-yellow, scattered with dark and whitish dots, dark dots more concentrated on merus, creating irregular patterns (Fig. 7 b). Ventral surface creamish-yellow, also sprinkled with microscopic dark and whitish dots.

Etymology. The specific epithet philippinensis is named after the type locality, the Philippines, denoting the discovery of this genus in the Philippines (see Remarks).

Habitat. The species inhabits the mid-intertidal zone of open, exposed sandy shores. Burrows are typical of Scopimera— a vertical, tube-like burrow, appearing as a circular hole on the surface, with radiating lines of small globular sand balls at the opening. The type locality, Iloilo, Panay I., is a semi-exposed sandy shore facing south, and had agricultural land-use directly adjacent to landward of the beach. The local distribution of the species appears to be restricted to the mouths of small streams, and often associated with polluted water. Locally S. philippinensis sp. nov. was not common, and generally neglected by local people due to their small size. The ghost crab Ocypode ceratophthalmus (Pallas, 1772), occurs sympatrically with S. philippinensis sp. nov., was abundant.

Distribution. At present, only known from Iloilo, Panay I., the Philippines.

Remarks. Scopimera philippinensis sp. nov. closely resembles other “normal form” congeners, especially S. curtelsona, by possessing a conspicuous molar on the cutting margin of the cheliped dactylus (Fig. 5 c, f) (even in small size individuals), and relatively smooth, broad carapaces (Fig. 5 a, e). However it clearly differs from S. curtelsona by the morphology of the male abdomen and G1. For S. philippinensis sp. nov., the sixth abdominal somite of males is distinctly broader than long, the proximal margin is much shorter, and the fifth much longer than broad, such that the entire abdomen appears “concave” along the lateral margin (Fig. 5 d); while for that of S. curtelsona, both breadth and length of sixth and fifth abdominal somites do not markedly differs, and the lateral margins of the 2 somites combined are only slightly converging towards the proximal end (Fig. 5 g). G1 morphologies of S. philippinensis sp. nov. and S. curtelsona are also diagnostic: the G1 of S. philippinensis. sp. nov. possesses a brush of setae near distal inner curve, among which extends a single extremely long seta (Fig. 6 a, b), while that of S. curtelsona is fringed by short setae, that are denser and slightly longer on the inner surface (Fig. 6 c, d).

Despite being commonly recorded from elsewhere across the entire region, no Scopimera species have been previously reported from the Philippines (Estampador 1937, 1959; Ward 1941; Serène 1968). This is especially peculiar because this area is otherwise considered to have the highest marine species biodiversity in the world (see Ng et al. (2009)). There have also been many collections made throughout the Philippines, and numerous studies have reported on the crab fauna in great detail (e.g., Garth & Kim (1983) on xanthids; Tan (1996) and Komatsu et al. (2004, 2005) on leucosiids; and Mendoza & Ng (2007) and Mendoza & Naruse (2009) on Macrophthalmus). Other much less conspicuous intertidal members of the Dotillidae have also been recorded, such as species of Dotilla, Ilyoplax and Tmethypocoelis (see Estampador 1959, and most recently Davie & Naruse (2010). Thus, the absence of previous records of Scopimera is either just an anomaly, or perhaps S. philippinensis sp. nov. is the only species present and does indeed have a very narrow range. This is a noteworthy issue that needs more research.

After reexamining the description of Scopimera curtelsona by Shen (1936), we realized that this species had been commonly misspelled as S. curtelsoma by recent authors (e.g. Dai & Yang 1991). Shen (1936) clearly used the spelling “ curtelsona ” consistently throughout the text. The International Code of Zoological Nomenclature (1999) Article 32.3 states “The correct original spelling of a name is to be preserved unaltered, except where it is mandatory to change the suffix or the gender ending under Article 34”. We thus follow this original spelling here.